php function array_key_exists and regular expressions

Question

Is it possible to use a regular expression with the php function array_key_exists()?

For example:

$exp = "my regex";  
array_key_exists($exp, $array);

Thank you!

Answer 1

there is no such function out of the box. you have to implement it with yourself.

Answer 2

No, I'm afraid not. You can iterate the array keys and perform matches on those:

$keys = array_keys($array);
foreach ($keys as $key)
  if (preg_match($exp, $key) == 1)
    return $array[$key];

Answer 3

You can extract the array keys using array_keys() and then use preg_grep() on that array:

function preg_array_key_exists($pattern, $array) {
    $keys = array_keys($array);    
    return (int) preg_grep($pattern,$keys);
}

.

$arr = array("abc"=>12,"dec"=>34,"fgh"=>56);

var_dump(preg_array_key_exists('/c$/',$arr)); // check if a key ends in 'c'.
var_dump(preg_array_key_exists('/x$/',$arr)); // check if a key ends in 'x'.

function preg_array_key_exists($pattern, $array) {
    // extract the keys.
    $keys = array_keys($array);    

    // convert the preg_grep() returned array to int..and return.
    // the ret value of preg_grep() will be an array of values
    // that match the pattern.
    return (int) preg_grep($pattern,$keys);
}

Output:

$php a.php
int(1)
int(0)